Control mechanism for hydraulic presses



June 6, 1939. K. c. MONROE CONTROL MECHANISM FOR HYDRAULIC PRESSES Filed May 17, 1937 2 Sheets-Sheet l ...illl .lrlun June 6, 1939. K. c. MONROE CONTROL MECHANISM FOR HYDRAULIC 4PRESSES Filed May 17, 1957` 2 Sheets-Sheet 2 I bulk.

Patented June 6, 1939 l UNH-ED STATES PATENT OFFICE CONTROL MECHAN ISM FOR HYDRAULIC PRESSES Application May 17, 1937;, Serial No. 142,952

7v Claims.

This. invention relates. to mechanism for con.- trolgling a hydraulic press. In the use of such presseson. certain operations, it is desired that the machine be foot-controlled, that the machine 5, continue to operate as, long as the foot pedal is depressed, and that the machine always come 'to rest in raised or inoperative position after the pedal is, released. f

'Bhismethod of operation has been heretofore Y llL- common in. mechanically operated presses, and

yit is the general, object of my invention to proj videlimproved controll mechanism through which these desired results may ,bel effectively and conveniently attained in a hydraulic machine.

f A, further object ofl my invention is to provide ajcontrol mechanism for a hydraulic press which nprmally holds the actuating mechanism of the press inoperative but which releases saidmechanism, forL continuous automatic operation when a 20, footy pedal is depressed by the operator.

invention further release to arrangements andncoinbinationsof parts which will be hereinaiter describedand morel particularly pointed outinthe appendedclaims. A preferredfiorm of the invention is shown in the drawings, in which Figi is a sideelevation of a hydraulic press Ealing-my improved control mechanism applied thereto; Eig, l? iS enlarged side View of certain parts snowplane- 1.:

Eig:V 2- is an enlargedV side elevation ofthe control mechanism;

Fig. r3 is, an enlarged side elevation of the main valve of the. hydraulic press, and f Fig. 4 is anenlarged detail View looking in the direction ofthe arrow 4;;in Fig, 2.

Referring. to-Fig. l; Ihave shown a hydraulic press .comprising abase or platen I0, an upright support.r l and atop frame member |2; A tool holder I4. is mounted to slide in vertical guideways lintheA front face of the support and is -connected .bya piston rod I6 to a piston slidablejn .a main cylinder lllinounted at the front y A45 ofrthetop; frame member l2.

Theupper andlower ends of the cylinder |8 are connected through pipes 2|) and .2| to amain valve,.Vprovided with a supply pipe 2,4.and an rexhaust .pipe or connection 25. Oil under pres- 50 surejisfurnishedto the supply pipe 24` froma pump,-,or v other suitable sourcev of supply.

. The main valve. preferably comprises a ,casing 31),. (Fig, 3)..;having a, longitudinal intake passage 55- ttid.i;rn'=il.A exhaustfpassase. 32connected to the-ex.- f

haust pipe 25.. Ports 33, 34, -and 36 connect the intake passage 3| with the valve cylinder 4i? in which apiston valve 4| is slidable. The valve 4| comprises a plurality of short piston elements spaced apart and mounted on a piston rod 42.

The exhaust passage 32 is connected by ports 44 and 4.5 to the valve cylinder 40. The pipes 28 and;v 2|v are connected to ports 45' and 41 in the casing 3B.

When the valve 4| is in the normal or inoperative position shown in Fig. 3, the ports 46 and 4l are closed, the intake `passage 3| is connected to the cylinder Ml through the intake ports 33 ands36, andthe cylinder is connected through the exhaust ports 44 and 45 to the exhaust passage 32, so that the output of the pump circulates freely. and is immediately returned through the exhaust pipe 25 to the pump or storage tank.

With the parts in the position described and Withthe ports 46 and 4l closed, no oil can enter or leave the cylinder |8 and the piston and tool holder are locked in raisedy position.

litho valve rod 42 and the piston valve 4| are moved downward, the exhaust port 45 will be closed,also the intake ports 33 and 34, and the intake port 35 will be connected through the port 4l and pipe 2d to the upper end of the main cylinder |8. At the same time the pipe 2| will be connected through the port- 46 and exhaust port-44 to the exhaust passage 32. A Working or down stroke of the press will then take place.

Iithe valve 4| is raised above the position shown in Fig. 3, the intake ports 35 and 36 and the exhaust port 44 will be closed, the intake passage 3| will be connected through the ports 34and lland the pipe 2| to the lower end of the cylinder l5, and the upper end of the cylinder will be connected through the pipe port 4l andexhaust port 45 to the exhaust passage 32, thus eiecting an upward or return movement of the piston and the tool holder i4 associ ated therewith.

The parts thus far described are of a more or less usual construction and are shown and described for purposes of illustration.

I Will now describe my improved mechanism for controlling the operation of the hydraulic machine previously described. For tin's purpose I providea bell crank 53 pivoted at 5| and having a .handle extension 52. The depending arm of the bell crank 5llis connected by'a link 53 to a bell` crank 5`4fmounted on a short shaft 55; The second arm 56of the bell crank 54 is connected bya link-Sito a lever 58, pivoted at 59 and con- 58 by means of a slot 89 and stud 8|.

supports the bell crank 54, and this arm 19 is connected by a link 1I to an end member 12 which is rsecured to the lower end of a reverse rod 13.

The reverse rod 13 is slidable in a bearing 14 (Fig. 1) Xedto the frame member 12, and is provided with upper. and lower stop collars 15 and 4 16. The/rod 13 passes freely through an opening in, a bracket 11 mounted on the tool holder I4 and is vertically moved therewith.

As the tool holder I4 moves up and down, the bracket 11 alternately engages the collars 15 and 16 and causes corresponding movements of the main valve, as will be hereinaft'er described.

The link 51 (Fig. 2) is connected to the lever This is to provide lost motion and effect a lag in the movement of the main valve, for a desired purpose.

A foot pedal 82 is pivoted at 83 and is mounted to swing between an upper stop 84 and a lower stop 85, both of which may be vertically adjusted. The pedal 82 is normally held in the raised position shown in Fig. 1 by a heavy spring 86, connected to the pedal through a rod 81.

A link 99 is pivoted at 9| to the pedal 82 and is provided at its upper end with an elongated slot 92 which receives a stud 93 on the bell crank 59. The end portions of the link 99 are threaded for longitudinal adjustment, and lock nuts 94 are provided to maintain the adjustment.

Having described the details of construction of my improved control mechanism, I will now described its operation.

The parts are shown in Fig. 1 in normal position, with the press inoperative and with the output of the pump by-passed to the exhaust. It will be noted that the pin 93 on the bell crank 59 is seated in the lower end'of the slot 92, so that the heavy spring 86 resists further movement of the bell crank 50. It will also be noted that the pivot 63 which connects the link 53 with the bell crank 54 is slightly beyond or to the right of the center line which connects the pivots 55 and 66. Furthermore, the lost motion has been taken up at the upper end of the link 51, so that the stud 8| is at the lower end of the slot 89.

The pedal 82 and heavy spring 86 thus act delinitely to hold the parts in neutral position and to prevent further movement of the valve V and operation of the press.

When the pedal 82 is depressed, the slot 92 in the link 99 is moved downward, so that the studl 93 thereafter swings free in the slot 92. I'hisref-A on the tool holder I4' engages the Acollar 16 and acts through the.' arm 19 to swing the bell crank-v 54 in an anti-clockwise direction to a point beyond dead center, whereupon the toggle spring 61 completes the movement to the left and thus accomplishes reverse movement of the piston rod 42 and piston elements in the main valve V.

The slot 89 in `the link 51 provides sufcient lag in the movement of the main valve so that the spring toggle members pass the dead center before the main valve is moved sufficiently to entirely cut off the oil feed to the main cylinder. This provision of lost motion and accompanying lag thus enables the machine to operate continuously so long as the foot pedal remains depressed.

Whenever the foot pedal is released, however, the link 99 will move upward, engaging the pin 93 and preventing movement of the bell crank 59 to the position shown in Fig. 2, as the toggle spring 61 is not strong enough to overcome the heavy spring 86.

The slotted link 92, however, permits free upp ward movement of the bell crank 59, so that the machine will not stop at the end of a down stroke but only as the next ensuing up stroke is completed. Consequently the machine always stops with the tool holder I4 in raised position, but will operate continuously as long as the foot pedal is held depressed.

It will` be understood that manual pressure may be applied to the handle 52 to overcome the spring 86 and thus effect independent control of the main valve in any manner desired.

While my improvements are of general application to hydraulic presses and to machines for performing similar operations, they are of particular utility when embodied in machines used for tube drawing operations. In such machines, extended tool travel is required, as the tubes may be long and the tool must be withdrawn a sub-r alternately in opposite directionsto spaced operative positions, and manually controlled means normally overpoweringsaid automatic means and preventing automatic movement of said valve subv stantially beyond neutral mid-position in onel direction only but leaving said automatic means free to move 'saidvalve inV the opposite direction.

2. In aA hydraulic press, in combination, hy-A draulic actuating mechanism, a reversingvalve: therefor, an actuating device for said valve, ,me--

chanical means to give said actuating device -the first part of its reversing movement, a spring to complete said movement, and manually contrlled means normally effective to preventv completion of said partial reversing movement of I said actuating device by said spring beyond neutral mid position in one direction only but leaving said actuating device freely movable by saidspring in the opposite direction to fully re verse said valve.

3. In a hydraulic machine having a tool holder, a hydraulic cylinder and piston connected to move said tool holder toward and from the work and a shiftable valve effective to direct a flow of oilunder pressure alternately to opposite ends of said cylinder, that improvement in control i Yspring-actuated element connected to move said shiftable valve,- automatic means to move said spring-actuated `element beyond neutral midposition alternately in opposite directions, and manually controlled means tolimit movement of vsaid spring-actuated element in one direction substantially to neutral mid-position but leaving said valve freely movable by said spring-actuated element in the oppositedirection.

4; In a hydraulic machine having a tool holder,

Aa hydraulic cylinder and piston connected to move said tool holder toward and from the workfa kshiftable valve effective to direct a i'low of oil under pressure alternately toopposite ends of relement passing substantially beyond neutral f mid-position in one direction only but leaving said valve freely movable by said spring-actuated element in the opposite direction.

5. In a hydraulic machine having a tool holder, a hydraulic cylinder and piston connected to move said tool holder toward and from the work and a shiftable valve eectivev to direct a ow of oil under pressure alternately to opposite ends of said cylinder, that improvement'in control mechanism for said machine which comprises a springactuated toggle element connected to move said shiftable valve, automatic means to move said spring-actuated element beyond dead center alternately in opposite directions, manual means to move said spring-actuated toggle element in either direction, and manually releasable means normally eiective to prevent movement of said manual means andtoggle element in one direction substantially beyond neutral mid-position but leaving said valve freely movable by said toggle element in the opposite direction.

6. In a hydraulic machine having a tool holder,

a hydraulic cylinder and piston connected to move said tool holder toward and from the Work and a shiftable ,double acting valve eifective to direct a ilow of oil under pressure alternately to opposite ends of said cylinder, that improvement in control mechanism for said machine which comprises a spring-actuated element connected to move said shiftable valve, said valve being in neutral mid-position when said spring-actuated element is in mid-position, automatic means eiective to move said spring-actuated element beyond neutral position alternately in opposite directions, means normally eiective to prevent completion of the movement of said springactuated element by said automatic means substantially beyond neutral mid-position in a direction to cause said valve to effect an advance movement of the tool holder toward the Work, and manual means to release said preventing means.

7. In a hydraulic machine having a tool holder, a hydraulic cylinder and piston connected to move said tool holder toward and from the Work and a shiftable double acting valve eiective to direct a ow of oil under pressure alternately to opposite ends of said cylinder, that improvement in control mechanism for said machine which comprises a spring-actuated toggle element connected to move said shiftable valve, said valve being in neutral mid-position when said spring-actuated element is in mid-position, automatic means eiective to move said spring-actuated toggle element beyond dead center alternately in opposite directions, a pedal associated with said spring-actuated element, and a spring to raise said pedal to normal position, thereby preventing completion of the shifting movement of said spring-actuated toggle element by said automatic means substantially beyond neutral mid-position in a direction to cause said valve to effect an advance movement of the tool holder toward the Work, and said pedal releasing said spring-actuated element for immediate movement by said automatic means when said pedal is depressed.

y KENNETH C. MONROE. 

